Sprite Atlas Unable to add packables in Unity2017 beta via scripting

In the 2D Experimental Release 2 thread, there is a script available that allows users to add packable objects to the SpriteAtlas:

Code (CSharp):

1. SpriteAtlas.AddPackableObjects(Object[] packables)

I'm currently experimenting with Unity2017.1.b07 beta and attempting to modify a SpriteAtlas via scripting in order to efficiently upgrade my old UI system to use the new 2D feature. However, there are currently no functions available to modify the SpriteAtlas packables.

Is there any timeline for when the updated SpriteAtlas API that was showcased in the Experiemental Release thread will be available in the public Unity2017 beta? In the interest of not using 3rd party plugins, would it be wiser to instead utilize the SpritePacker if modifying sprite atlases via editor scripts is currently a high priority for me?